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2021 Journal article Open Access OPEN

The natural frequencies of masonry beams
Girardi M.
The present paper aims at analytically evaluating the natural frequencies of cracked slender masonry elements. The problem is dealt with in the framework of linear perturbation, and the small oscillations of the structure are studied under loaded conditions, after the equilibrium for permanent loads has been achieved. A masonry beam element made of no-tension (masonry-like) material is considered, and some explicit expressions of the beam's fundamental frequency as a function of the external loads and the amplitude of imposed deformations are derived. The analytical results are validated via finite-element analysis.Source: Archive of applied mechanics (1991) (2021): 2369–2379. doi:10.1007/s00419-021-01887-4
DOI: 10.1007/s00419-021-01887-4

See at: arXiv.org e-Print Archive Open Access | Archive of Applied Mechanics Open Access | ISTI Repository Open Access | Archive of Applied Mechanics Restricted | Archive of Applied Mechanics Restricted | Archive of Applied Mechanics Restricted | Archive of Applied Mechanics Restricted | Archive of Applied Mechanics Restricted | CNR ExploRA Restricted


2021 Other Open Access OPEN

Torri in... movimento. Tutela e sicurezza nel progetto Soul del CNR
Girardi M., Padovani C., Pellegrini D., Azzara R. M.
Descrizione del progetto SOUL - Sismologia urbana nel centro storico di Lucca, finanziato dalla Fondazione Cassa di Risparmio di Lucca (2019-2022).

See at: CNR ExploRA Open Access | www.fondazionecarilucca.it Open Access


2021 Conference article Open Access OPEN

Influence of temperature on the structural behaviour of masonry buildings
Girardi M., Padovani C., Pellegrini D.
This paper investigates the mechanical behaviour of heritage structures subjected to seasonal temperature variations. To this end, the constitutive equation of masonry-like materials, which has been embedded in the finite element code NOSA-ITACA (www.nosaitaca.it), is used to model the static and dynamic behaviour of simple arched masonry structures subjected to thermal loads.Source: SAHC 2021 - 12th International Conference on Structural Analysis of Historical Constructions, pp. 2031–2042, Online event, 29/09/2021 - 01/10/2021

See at: CNR ExploRA Open Access


2020 Journal article Open Access OPEN

Dynamic characterization of progressively damaged segmental masonry arches with one settled support: experimental and numerical analyses
Masciotta M. G., Pellegrini D., Girardi M., Padovani C., Barontini A., Lourenço P. B., Brigante D., Fabbrocino G.
This paper aims to explore the dynamic behavior of a segmental masonry arch subjected to increasing horizontal displacements of one support. To this end, output-only dynamic identification techniques are first used to track the evolution of the dynamic features of the system under progressive damage scenarios and evaluate their sensitivity to settlement-induced cracks. Considerations on the structural response of the segmental arch up to failure are also included. Then, a numerical procedure coupling linear perturbation and modal analysis is applied to simulate the dynamic behavior of the arch over consecutive scenarios, taking into account the influence of the damage on the structure's dynamic properties in an automatic way. The combination of experimental and numerical analyses allows to fully investigate the dynamics of the cracked masonry arch and to shed light on relevant aspects about the effects of settlement-induced cracks on the modal blueprints of masonry arches.Source: Frattura e Integrità Strutturale (2020). doi:10.3221/IGF-ESIS.51.31
DOI: 10.3221/igf-esis.51.31

See at: Frattura ed Integrità Strutturale Open Access | ISTI Repository Open Access | CNR ExploRA Open Access | Frattura ed Integrità Strutturale Open Access | Fracture and Structural Integrity Open Access


2020 Journal article Open Access OPEN

Long-term dynamic monitoring of medieval masonry towers
Azzara R. M., Girardi M., Iafolla V., Padovani C., Pellegrini D.
The aim of the paper is to present and discuss the results of an ambient vibration monitoring campaign conducted in the old town of Lucca, over the period 2015-2018. Despite the low level of the ambient vibrations in the historic center, using high-sensitivity instrumentation allowed the authors to measure and study the dynamic behavior of two medieval masonry towers: the San Frediano belfry and the Clock Tower. The main results of the dynamic identification of the towers are summarized, together with the variation over time of their dynamic properties. Some insights on the towers' response to the anthropic activities in the historic center are also presented. Finally, a finite element simulation is performed with the aim of assessing the influence of temperature variations on the towers' natural frequencies; good agreement is found between numerical and experimental results. The paper provides the scientific and technical community with a detailed report on a singular experiment in the field of architectural heritage.Source: Frontiers in built environment Online (2020). doi:10.3389/fbuil.2020.00009
DOI: 10.3389/fbuil.2020.00009

See at: Frontiers in Built Environment Open Access | Frontiers in Built Environment Open Access | ISTI Repository Open Access | CNR ExploRA Open Access | Frontiers in Built Environment Open Access | Frontiers in Built Environment Open Access | Frontiers in Built Environment Open Access


2020 Journal article Open Access OPEN

Wireless sensor networks for continuous structural health monitoring of historic masonry towers
Barsocchi P., Bartoli G., Betti M., Girardi M., Mammolito S., Pellegrini D., Zini G.
The recent developments of micro-electro-mechanical systems and wireless sensor networks allow today the use of low-cost and small-size sensors for continuous monitoring of civil structures. Both these features are very important for the low impact of the sensor grid in heritage structures, ensuring a low-cost and sustainable dynamic monitoring system. Over the last 20 years the use of sensor networks for continuous monitoring has received a growing interest. Anyway, still numerous questions remain opened about the sensitivity of measurement devices, the optimization of number and positioning of sensors, the energy efficiency of the network, and the development of algorithms for real-time data analysis. This paper, based on the aforementioned motivations, discusses about a monitoring system made of micro-electro-mechanical sensors connected through a wireless network. The architecture of the wireless sensor network and the automatized procedure proposed for the continuous processing of the recorded signals are discussed and described with reference to an explicative masonry tower case study. It is believed that the proposed technologies can provide an economical and relatively non-invasive tool for real-time structural monitoring and that, moreover, the availability of large amounts of data from actual measurements can give effective information on the structural behaviour of historic constructions.Source: International journal of architectural heritage (2020). doi:10.1080/15583058.2020.1719229
DOI: 10.1080/15583058.2020.1719229

See at: ISTI Repository Open Access | International Journal of Architectural Heritage Restricted | International Journal of Architectural Heritage Restricted | CNR ExploRA Restricted | www.tandfonline.com Restricted | International Journal of Architectural Heritage Restricted | International Journal of Architectural Heritage Restricted


2020 Conference article Open Access OPEN

FE model updating of masonry towers: modeling and numerical issues
Azzara R. M., Girardi M., Padovani C., Pellegrini D., Robol L.
The goal of the paper is to investigate the role of soil-structure interaction in modeling the dy-namic behavior of masonry towers. The study, conducted on the bell tower of the Basilica of San Frediano in Lucca (Italy), is based on both experimental and numerical results. The former were collected during an experimental campaign carried out on the tower using seismometric stations, while the latter have been obtained via the modal analysis and model updating proce-dures implemented in the finite element code NOSA-ITACA. Combining experimental and nu-merical outcomes made it possible to assess the influence of the soil, modeled as a system of elastic springs, on the natural frequencies of the tower. Finite element models of the tower have been calibrated by taking the presence of the adjacent church into account and choosing differ-ent unknown parameters, including the soil stiffness.Source: EURODYN 2020 XI International Conference on Structural Dynamics, pp. 2285–2298, 25/11/2020

See at: eurodyn2020.org Open Access | ISTI Repository Open Access | CNR ExploRA Open Access


2020 Conference article Open Access OPEN

A multidisciplinary approach integrating geomatics, dynamic field testing and finite element modelling to evaluate the conservation state of the guimaraes castle's tower keep
Sánchez-aparicio L. J., Masciotta M. G., Pellegrini D., Conde B., Girardi M., Padovani C., Ramos L. F., Riveiro B.
The development of realistic numerical models able to replicate as closely as possible the actual structural behaviour of heritage buildings is crucial for a thorough assessment of their structur-al performance against exceptional scenarios. In this regard, higher accuracy can be achieved by leveraging a multidisciplinary approach that integrates multiple contributions from different fields, such as geomatics, dynamics and computational modelling. In the present paper, this strategy is applied to the tower keep of the Guimarães castle, in Por-tugal, a masonry fortified structure dating back to the X century. Starting from an accurate la-ser scanner survey, a detailed numerical model has been created resorting to efficient algo-rithms able to represent complex situations. Furthermore, by exploiting the dynamic properties extracted from the processing of vibration data collected during field dynamic testing, the me-chanical characteristics of the constituent materials of the tower have been estimated by means of a model updating technique embedded in a trust-region scheme implemented in the NOSA-ITACA code. The results obtained so far allowed to establish valuable baseline information that will be of pivotal importance to catch possible changes in the tower's response and to perform more in-depth structural analyses.Source: EURODYN 2020 XI International Conference on Structural Dynamics, pp. 2310–2322, 25/11/2020

See at: eurodyn2020.org Open Access | ISTI Repository Open Access | CNR ExploRA Open Access


2020 Journal article Open Access OPEN

A finite element model updating method based on global optimization
Girardi M., Padovani C., Pellegrini D., Robol L.
Finite element model updating of a structure made of linear elastic materials is based on the solution of a minimization problem. The goal is to find some unknown parameters of the finite element model (elastic moduli, mass densities, constraints and boundary conditions) that minimize an objective function which evaluates the discrepancy between experimental and numerical dynamic properties. The objective function depends nonlinearly on the parameters and may have multiple local minimum points. This paper presents a numerical method able to find a global minimum point and assess its reliability. The numerical method has been tested on two simulated examples - a masonry tower and a domed temple - and validated via a generic genetic algorithm and a global sensitivity analysis tool. A real case study monitored under operational conditions has also been addressed, and the structure's experimental modal properties have been used in the model updating procedure to estimate the mechanical properties of its constituent materials.Source: Mechanical systems and signal processing (2020). doi:10.1016/j.ymssp.2020.107372
DOI: 10.1016/j.ymssp.2020.107372

See at: Mechanical Systems and Signal Processing Open Access | ISTI Repository Open Access | Mechanical Systems and Signal Processing Restricted | Mechanical Systems and Signal Processing Restricted | Mechanical Systems and Signal Processing Restricted | Mechanical Systems and Signal Processing Restricted | Mechanical Systems and Signal Processing Restricted | CNR ExploRA Restricted | www.sciencedirect.com Restricted | Mechanical Systems and Signal Processing Restricted


2020 Report Restricted

Progetto SOUL - Simologia urbana nel centro storico di Lucca
Girardi M., Padovani C., Pellegrini D., Azzara R. M.
Progetto SOUL - Sismologia urbana nel centro storico di Lucca. Relazione sulle attività condotte nel primo anno di progetto (15 novembre 2019 - 15 novembre 2020).Source: ISTI Project report, Soul, 2020

See at: CNR ExploRA Restricted


2019 Journal article Open Access OPEN

Modal analysis of masonry structures
Girardi M., Padovani C., Pellegrini D.
This paper presents a new numerical tool for evaluating the vibration frequencies and mode shapes of masonry buildings in the presence of cracks. The algorithm has been implemented within the NOSA-ITACA code, which models masonry as a nonlinear elastic material with zero tensile strength. Some case studies are reported, and the differences between linear and nonlinear behaviour are highlighted.Source: Mathematics and mechanics of solids 24 (2019): 616–636. doi:10.1177/1081286517751837
DOI: 10.1177/1081286517751837

See at: arXiv.org e-Print Archive Open Access | Mathematics and Mechanics of Solids Open Access | ISTI Repository Open Access | Mathematics and Mechanics of Solids Restricted | Mathematics and Mechanics of Solids Restricted | Mathematics and Mechanics of Solids Restricted | Mathematics and Mechanics of Solids Restricted | Mathematics and Mechanics of Solids Restricted | Mathematics and Mechanics of Solids Restricted | CNR ExploRA Restricted | Mathematics and Mechanics of Solids Restricted


2019 Report Unknown

MOSCARDO - Tecnologie ICT per il MOnitoraggio Strutturale di Costruzioni Antiche basato su Reti di sensori wireless e DrOni [MMS Lab, Rapporto tecnico n. 2]
Girardi M., Padovani C., Pellegrini D., Robol L.
MOSCARDO - ICT technologies for structural monitoring of age-old constructions based on wireless sensor networks and drones. Description of the activities conducted by the Mechanics of Materials and Structures Laboratory of ISTI-CNR. Project Report n. 2.Source: Project report, MOSCARDO, 2019

See at: CNR ExploRA


2019 Journal article Open Access OPEN

Model updating procedure to enhance structural analysis in FE Code NOSA-ITACA
Girardi M., Padovani C., Pellegrini D., Robol L.
This paper describes a model updating procedure implemented in NOSA-ITACA, a finite-element (FE) code for the structural analysis of masonry constructions of historical interest. The procedure, aimed at matching experimental frequencies and mode shapes, allows for fine-tuning the calculations of the free parameters in the model. The numerical method is briefly described, and some issues related to its robustness are addressed. The procedure is then applied to a simple case study and two historical structures in Tuscany, the Clock Tower in Lucca and the Maddalena Bridge in Borgo a Mozzano.Source: Journal of performance of constructed facilities 33 (2019): 04019041-1–04019041-16. doi:10.1061/(ASCE)CF.1943-5509.0001303
DOI: 10.1061/(asce)cf.1943-5509.0001303

See at: Journal of Performance of Constructed Facilities Open Access | Archivio della Ricerca - Università di Pisa Open Access | ISTI Repository Open Access | Journal of Performance of Constructed Facilities Restricted | Journal of Performance of Constructed Facilities Restricted | Journal of Performance of Constructed Facilities Restricted | Journal of Performance of Constructed Facilities Restricted | Journal of Performance of Constructed Facilities Restricted | CNR ExploRA Restricted


2019 Report Open Access OPEN

ISTI Young Researcher Award "Matteo Dellepiane" - Edition 2019
Barsocchi P., Candela L., Crivello A., Esuli A., Ferrari A., Girardi M., Guidotti R., Lonetti F., Malomo L., Moroni D., Nardini F. M., Pappalardo L., Rinzivillo S., Rossetti G., Robol L.
The ISTI Young Researcher Award (YRA) selects yearly the best young staff members working at Institute of Information Science and Technologies (ISTI). This award focuses on quality and quantity of the scientific production. In particular, the award is granted to the best young staff members (less than 35 years old) by assessing their scientific production in the year preceding the award. This report documents the selection procedure and the results of the 2019 YRA edition. From the 2019 edition on the award is named as "Matteo Dellepiane", being dedicated to a bright ISTI researcher who prematurely left us and who contributed a lot to the YRA initiative from its early start.Source: ISTI Technical reports, 2019

See at: ISTI Repository Open Access | CNR ExploRA Open Access


2019 Journal article Open Access OPEN

Experimental and numerical investigations on the seismic behaviour of the San Frediano bell tower in Lucca
Azzara R. M., Girardi M., Padovani C., Pellegrini D.
This paper presents a study on the seismic response of the San Frediano bell tower in Lucca. The tower's ambient vibrations were continuously monitored for about one year, form October 2015 to October 2016. During this monitoring campaign, many seismic events were recorded on the tower and the most relevant turned out to be the Amatrice earthquake, which struck Central Italy on 24 August 2016. The paper begins with a review of the experimental results obtained on the tower's dynamic behaviour. Then, a finite element numerical model of the tower is presented and validated via model updating, by assuming the tower's constituent materials to be unable to withstand tensile stresses. The experimental records of the Amatrice earthquake are also included in the analysis to assess the dynamic behaviour of the finite element model under ambient vibration. Finally, a numerical simulation is performed of the tower subjected to the Lunigiana earth-quake, recorded in Fivizzano (Tuscany) on 21 June 2013: the results of the dynamic analysis are presented and discussed.Source: Annals of geophysics (Online) 62 (2019). doi:10.4401/ag-8025
DOI: 10.4401/ag-8025

See at: Annals of Geophysics Open Access | ISTI Repository Open Access | ISTI Repository Open Access | CNR ExploRA Open Access | Annals of Geophysics Open Access | Annals of Geophysics Open Access | www.annalsofgeophysics.eu Open Access


2019 Conference article Open Access OPEN

Experimental and Numerical Investigations of a Segmental Masonry Arch Subjected to Horizontal Settlements
Masciotta M. G., Brigante D., Barontini A., Pellegrini D., Lourenço P. B., Fabbrocino G., Padovani C., Girardi M.
Settlements represent one of the main causes of collapse in arched structures. The stiffness degradation and strength reduction associated with these slow long-term movements are reflected in changes of the dynamic properties of the system (frequencies, mode shapes and damping ratios). The correct dynamic characterization of the nonlinear behaviour of masonry arches undergoing supports settlements is therefore fundamental to timely detect the occurrence of serious damage mechanisms and prevent unexpected failures. This paper aims to investigate the dynamic behaviour of a segmental masonry arch subjected to stepwise horizontal displacements of one support. To this end, output-only dynamic identification techniques are first used to estimate the experimental dynamic properties of the system under progressive damage scenarios. Then, a numerical procedure coupling linear perturbation and modal analysis is applied to evaluate frequencies and mode shapes of the arch, taking into account the actual crack distribution induced by the settlements. The combination of experimental and numerical investigations allows to explore in detail the dynamics of the settled masonry arch as well as its potential collapse mechanism.Source: Arch 2019, Porto, Portugal, 2-4/10/2019
DOI: 10.1007/978-3-030-29227-0_43

See at: ISTI Repository Open Access | academic.microsoft.com Restricted | iris.unimol.it Restricted | link.springer.com Restricted | link.springer.com Restricted | CNR ExploRA Restricted


2019 Conference article Open Access OPEN

Nonlinear FE model updating for masonry constructions via linear perturbation and modal analysis
Girardi M., Padovani C., Pellegrini D., Robol L.
This paper describes the automated nonlinear model updating procedure for ma-sonry structures implemented in the NOSA-ITACA code. The algorithm, aimed at matchingnumerical and experimental natural frequencies and mode shapes, combines nonlinear staticanalysis, linear perturbation and modal analysis and allows fine-tuning the free parametersof the model. The numerical method is applied to two simple case studies, which prove itseffectiveness.Source: COMPDYN 2019, Crete, Greece, 24-26/06/2019

See at: 2019.compdyn.org Open Access | ISTI Repository Open Access | CNR ExploRA Open Access


2019 Contribution to conference Open Access OPEN

FE model updating of the Matilde donjon in Livorno
Azzara R. M., Girardi M., Padovani C., Pellegrini D., Robol L.
The paper describes a preliminary experimental campaign conducted on The Matilde donjon in Livorno (Italy) aimed to characterize its dynamic behaviour, and the corresponding numerical analysis conducted on a FE model created via the NOSA-ITACA code.Source: CIVIL-COMP 2019, Riva del Garda Italy, 16-19/09/2019

See at: ISTI Repository Open Access | CNR ExploRA Open Access


2019 Contribution to conference Open Access OPEN

FE model updating: sensitivity, reliability and regularization issues
Girardi M., Padovani C., Pellegrini D., Robol L.
Combining ambient vibration monitoring and finite element (FE) modelling through suitable model updating procedures allows for obtaining an estimate of the boundary conditions and mechanical material properties of engineering structures. Application of FE model updating to historical buildings is relatively recent and involves the solution of a constrained minimum problem, whose objective function is generally expressed as the discrepancy between experimental and numerical quantities, such as natural frequencies and mode shapes. The paper presents an algorithm for FE model updating based on the construction of local parametric reduced-order models embedded in a trust-region scheme and implemented in NOSA-ITACA, a non-commercial FE code developed by the authors. The algorithm exploits the structure of the stiffness and mass matrices and the fact that only a few of the smallest eigenvalues have to be calculated. This new procedure enables to compute eigenvalues and eigenvectors cheaply and thus to solve the minimum problem very efficiently. Besides reducing the overall computation time of the numerical process and enabling the accurate analysis of large scale models with little effort, the proposed algorithm allows for getting information on both the reliability of the solution and its sensitivity to noisy experimental data. Some case studies are presented and discussed and the adoption of regularization techniques to recover meaningful solutions investigated.Source: XXIV Congresso AIMETA 2019, pp. 286–286, Roma, 15-19/10/2019

See at: ISTI Repository Open Access | CNR ExploRA Open Access


2019 Conference article Open Access OPEN

Structural health monitoring of ancient constructions within the framework of the MOSCARDO project
Bartoli G., Betti M., Girardi M., Padovani C., Pellegrini D., Pintucchi B., Zini G.
This paper presents some results about the MOSCARDO system, a structural health monitoring platform specifically developed for long-term measurement of heritage structures. The main features of the system are shown with reference to a case study: the Voltone in Livorno (Italy).Source: 3rd International Conference on International Conference on Recent Advances in Nonlinear Design, Resilience and Rehabilitation of Structures, CoRASS 2019, Coimbra, 16-18/10/2019

See at: ISTI Repository Open Access | CNR ExploRA Open Access